A one-shot I joined last week was tasked with fighting a bunch of tribal orcs. At one point the orcs drew longbows (with what was at least a +6 to hit as the DM was asking if 25 AC hits). At this, everyone at the table got upset as, according to them, “the monster manual orcs use javelins 30/120 and occasionally chuck spears 20/60; and have a +5 to hit but only with melee weapons.”

I'm used to DMs customizing monsters and deviating from the monster book. I had never made the assumption that we'd be fighting cookie cutter monsters, but the rest of that group seems to feel that that should be the norm.

Now I'm concerned that I've misunderstood how D&D 5e is supposed to be run. I am DMing a 5e game this weekend, I'm now worried that people will have the same reaction to my creatures when I deviate from the book.

Are 5e monsters intended to be used exactly as published in the MM, or is it within the rules and common custom to change them?

8 Answers
8

It's not only not wrong, it's encouraged in the DMG and the MM

The Dungeon Masters Guide (DMG; pp. 273-282) has a set of guidelines for making your own monsters. This is alluded to in the Monster Manual (MM; p. 6) in the green box entitled "Modifying Creatures." Your problem with the longbow bearing orcs was their to hit bonus, not the fact that they were using long bows.

... fighting a bunch of tribal orcs. At one point the orcs drew longbows (with what was at least a +6 to hit as the DM was asking if 25 AC hits). At this, everyone at the table got upset as, according to them, “the monster manual orcs use javelins 30/120 and occasionally chuck spears 20/60; and have a +5 to hit but only with melee weapons.”

This looks like a CR adjustment issue. Per the DMG tools, +6 to attack (proficiency bonus + ability score) is what a CR 3 creature gets(+2 and +4), but the damage per round still points toward CR 1/2 (6-8). Normal orcs are CR 1/2. (DMG; Monster Statistics by Challenge Rating; p. 274).

The usual orc dexterity stat (12 Dex) provides a +1 bonus, not a +4 bonus(Dex 18-19). When added to the CR 1/2's +2 proficiency bonus an orc gets +3 to attack bonus (total) with a long bow. The +6 to hit was a significant difference in chances to hit for the orcs. The DMG points to a CR of 1 since the attack bonus is more than 2 greater than the basic monster. That moves the orcs' CR from 1/2 to 1: not due to the longbows, but due to to hit bonus.

One rule overrides all others: the DM is the final authority on how the rules work in play (XGtE, p. 5)(thanks to @SeraphsWrath for the note).

... but check your modifications against the monster creation / customization material in the DMG. This will give you an idea of how much challenge a custom monster will offer to your players. It's not an exact measure, but it should get you in the ballpark.

Experience

In my brother's campaign, our party of 5 ran into 8 orcs armed with the usual great axes and also with long bows. (Three snipers in the trees!) We were mixed levels, 2 and 3. That was a tough fight, but we were not at extreme range
(less than 100' to start) and they closed distance in a hurry (aggressive) as the fight progressed. We found that the great axes were a much more serious problem than the long bows -- but the orcs were not +6 to hit with bows.

@Crovaxon made a useful suggestion in a comment on using ability checks to complement monster customization.

If the players know the lore of the world you play in and/or know the
monster manual itself, they might come into the game with certain
expectations. But modifying the monster is still fine and a fun way to
encounter new stuff! Just inform your players beforehand that you
might modify the enemies they will encounter. Keep in mind what the
Monster Manual gives you in terms of lore for the creatures you
modify. If your modifications touch upon these, encourage your players
to make Knowledge Rolls and incorporate your mods into your answer.

\$\begingroup\$Don't forget page 5 in Xanathar's: One rule overrides all others: the DM is the final authority on how the rules work in play.\$\endgroup\$
– SeraphsWrathAug 11 '18 at 18:00

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\$\begingroup\$This is an excellent amount of research, calculation and data on your part Korvin, thank you. I really failed to grasp how much of a difference the dex bonus alone was adding to their challenge ratings. Perhaps the range issue is merely mechanical, changing the action economy of the fight, but the stat block change is definitely something to complain about. I think I'm starting to understand all the hubbub.\$\endgroup\$
– AshRandomAug 12 '18 at 11:41

2

\$\begingroup\$One addition to an otherwise great answer: If the players know the lore of the world you play in and/or know the monster manual itself, they might come into the game with certain expectations. But modifying the monster is still fine and a fun way to encounter new stuff! Just inform your players beforehand that you might modify the enemies they will encounter. Keep in mind what the Monster Manual gives you in terms of lore for the creatures you modify. If your modifications touch upon these, encourage your players to make Knowledge Rolls and incorporate your mods into your answer.\$\endgroup\$
– CrovaxonAug 13 '18 at 11:53

There's a very simple (implicit) rule that is very much put on a pedestal in D&D, especially in 5e:

If You [the GM] don't like it, Change It!

What does that mean? Well...

If the GM feels that their orc tribe is equipped with Longbows and has a +6 for that, this is their decision and it is not in the right of the players to challenge this decision because the GM is the world. 5e makes it a big part that the GM has every right to change the world as they deem fit, to invent monsters and change them as they want.

For example page 5 of Xanathar's guide to everything:

One rule overrides all others: the DM is the final authority on how
the rules work in play.

And in the Monster Manual itself there is this:

Feel free to tweak an existing creature to make it into something more
useful for you.

In this vein, the GM did decide to change the Orcs to be something they want: Killersniperorcs. True, their challenge rating was obviously too high for your party, but it was their right to do so.

But the Players have no basis for their argument if it starts with "In the monster manual..." because D&D 5e is a game that practically yells at the GM "Invent your own stuff, we just give you a toybox".This lazy invent everything yourself attitude is what I hate in some games. And this very thing about 5e takes away the players very ability to challenge GM decisions on the basis of the monster-manual: The GM is the final and only arbitrator, especially when it comes to monster statistics as the 2 quotes above point out.

And they have to be able to do this tweaking because there is one big thing that designing monsters in D&D5e demands of the GM: Playtest it.

TL;DR

As mean as it sounds: don't challenge the decision of the change in itself, ask the GM to explain how challenging they thought this should be. They might be still playtesting this specific variant of orc and adjusting it for further use!

Monsters exactly as MM? Not really.

The MM says:

Modifying Creatures

Despite the Versatile collection of Monsters in this book, you might be at a loss when it comes to finding the perfect creature for part of an adventure. Feel free to tweak an existing creature to make it into something more useful for you, perhaps by borrowing a trait or two from a different monster or by using a variant or template, such as the ones in this book. Keep in mind that modifying a monster, including when you apply a template to it, might change its challenge rating.

Let us make the Orc as an example.

The MM version uses Greataxe and Javelin as weapons, both at +5 to hit (+2 from proficiency and +3 from Strength). You could say that a tribe of orcs from a certain region has the tradition of fighting larger monsters and hunt flying prey from afar and that tradition is reflected in their weapons of choice; Pike (Reach weapon) and Longbow (Ranged weapon with very long reach).

They kept their proficiency bonus and added the respective ability modifier to their attacks. They adapted to fighting Large creatures and adopted a reach weapon for safety reasons and while the hit chance from their ranged attack decreased, their range increased a lot, allowing them to attack earlier from farther away. These still are the same CR 1/2 orcs.

You (and your DM) are right. Customizing monsters is part of the game

As others have said, changing up monsters from the MM is encouraged. This is especially useful if you have players who know, for example, that orcs only use javelins with a +5 to hit. Modifying them slightly to be a bit better trained to up the challenge is completely within the bounds of a normal D&D 5e table. This enables the DM to properly challenge, narrate, and, as is sometimes necessary, prevent metagaming.

In my campaigns, I usually only have about 1/2 of the enemies straight from the MM unmodified. This has allowed lower level parties to fight weaker versions of more interesting enemies, higher level parties enjoy fighting stronger versions of more thematic enemies, or completely custom fights with raid-like mechanics that the party can learn and adapt to. The key is to know where they are and balance it for that.

Addressing the DM, and not the problem

This really bothers me, though. Unless the fight was the DM obviously having fun smashing the players, their reaction should have been along the lines of

takes cover

"Since when did orcs have such good aim? And where did they get the longbows?"

deal with it in character

Bringing up something that bothers you is obviously fine, but solving an in-game issue by trying to appeal to the DM is like buying loot crates to beat a PvE game. Just don't.

You know whether it was unfair

I wasn't there, I don't. Was the challenge too hard for the party or was the party unprepared because they were metagaming on the way in? If it's the former, your DM might need to work on balancing. Based on them rattling off the armaments and stat lines mid-combat, though, I feel it's the latter.

TL;DR

Customizing existing monsters or even creating new ones is part of D&D 5e and is strongly encouraged. Balancing may be an issue but this sounds more like a desire from the other players to have a metagaming advantage. Most importantly, solving problems in the game's world by appealing to the DM is a party foul. Solve it in character and then talk after.

No, DnD5e is not supposed to have only cookie-cutter monsters from the Monster Manual. Inventing own content is not just permitted, it is encouraged. The Monster Manual is supposed to serve:

As a repository of ready-to-play opponents the DM can insert into their game when they don't feel like inventing their own

As an example for the DM for how the sheets of balanced monsters should look

There are three reasons I could imagine why the players might have reacted negatively to the decision to modify the standard orcs by giving them longbows:

Replacing spears and javelines with longbows made the encounter too hard for them. You don't write how the battle was going, but "And now they suddenly all have better weapons" might have sounded like cheap DMing. If they were already losing, it might have looked like a killer-DM move (a killer DM is a DM who thinks they "win" the game by killing all player-characters).

It conflicted with assumptions about the game mechanics. When the players learned the game, they got the impression that the game is to be played as written in the rulebook. This appears to be a communication failure while teaching the game.

It conflicted with assumptions about the game lore. The players might have had a certain conception about how orcs are supposed to fight. Orcs with longbows might have seemed out-of-character to them. Especially if they are tribal orcs who are generally assumed to use brutish and crude weapons and tactics with little finesse. Just like you wouldn't expect elves to do a berserker charge with great axes or dwarfes to fence with epees. Having NPCs act against stereotypes can be interesting, but you need to provide some plausible explanation why they would do that.

I do not know your group and I haven't participated in your game, so I do not know which of these reasons made the players upset.

\$\begingroup\$Concerning the last point, why does the DM need to explain changes they make to the lore?\$\endgroup\$
– RubiksmooseAug 13 '18 at 12:33

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\$\begingroup\$@Rubiksmoose Because player go into a game with certain expectations. In a DnD games, it's usually to experience Tolkien-inspired heroic fantasy. To give a more exaggerated example: When you agreed to play DnD, and the DM suddenly has an UFO land in front of the PCs with an alien inviting them to have a space adventure, wouldn't you also feel that the DM mislead you about what to expect from the game?\$\endgroup\$
– PhilippAug 13 '18 at 12:39

3

\$\begingroup\$@Rubiksmoose the lore should be a common shared understanding of the world. If you deviate from the "default lore", then this should be made explicit to ensure that the understanding is still common - tribal orcs using longbows should come as a surprise to players only if it's also a surprise to in-game PCs and NPCs; if in-game PCs and NPCs would shrug and say "yep, tribal orcs tend to do that" then this should be also communicated to players the moment this fact becomes relevant i.e. before the longbows come out - simply to ensure that players know the relevant parts of what PCs know.\$\endgroup\$
– PeterisAug 13 '18 at 15:03

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\$\begingroup\$@Peteris I understand this, but the question is asking about rules and common practices. My main point is that this answer says DMs "need" to do this which implies there is some rule or something forcing them to. There is not, but there are certainly reasons they should do it which I think would help if it were clarified in this answer.\$\endgroup\$
– RubiksmooseAug 13 '18 at 15:13

1

\$\begingroup\$This answer is written as if it is skipping details of the question. For example, the question isn’t asked by the DM of the session, but the answer keeps calling the DM “you”. You may wish to audit the answer’s accuracy relative to the question in order to find details where it can be improved with edits.\$\endgroup\$
– SevenSidedDieAug 13 '18 at 16:39

Classed NPCs

You may not have been fighting generic monsters. As a DM I have filled out character sheets for NPCs that my players have fought. This means some of the monsters are a much higher to hit than I would have liked (like a +4 dex rouge), but other stats could also be lower.

Even if that is the case like everyone states above, the DM can just change something if they feel it is too strong.

Tactics

in DnD things like experience are based on CR. CR is a raw power scale and can do things wrong at times. Specifically when tactics are put into play. When a DM wants to kick up the difficulty of a task without putting more XP or loot into the player hands they can bring out tactics.

This tactic you were against is a generic "softening before engaging" and is inspired by roman legions. Romans would pepper their foes with arrows before marching in to fight. This makes your targets start with less effective health and makes the players slightly more cautious.

There are many other tactics but the result is the same, putting skills together that are usefully separately into highly effective strategies.

The DM is not in the wrong

There may be a miscommunication about the style of game but DMs do not want to hold your hand all the time. They want a challenge to and may overestimate the parties abilities. The party could also just not expect something with a modicum of intellect.

These monsters and groups have survived before and after your parties arrival. They will have specialized ways of fighting and the party needs to learn their foe to fight them properly. Take this as a learning experience, some things are deceptively hard just because they actually know what they are doing.

Yes, it is badly wrong, unless the characters have been dropped in that world, in front of that orks, just 5 minutes before. Or they are all 5 years old.

Forget about players for a moment.

What you have is a group of adult people who have been living in a specific world, with a specific culture, surrounded by other culture more or less known, for years. This people are a (somehow) skilled group of adventurers, who routinely travel the world for many different reason, and thus are well prepared and informed.

They know that orks do not use bows. Everybody knows it, even the most stupid of the farmer, the same way every living being on a random planet (let's call it "Earth") in a different plane of existence knows that humans do not shoot lasers from their eyes.

Now, this is what the characters know. They know plants, they know how to behave in taverns, they know how to use weapons, they know how to use magic...but the players know nothing of this. How can players, thus, cross the interdimensional abyss that divide them from their characters? How can a player roleplay someone in a different universe, without any basic knowledge if that universe?

Well, the answer is simple: reading manuals, reading books, or getting those information by the master. That is the contract between players and the DM, it's binding because it's the only way the players can have a chance to effectively play a character in that world.

Are orks routinely using bows in that world? Well, then that should have been a well known fact.

\$\begingroup\$The DM is not telling everything about the monsters because they are playing in a world which lore is common knowledge. Then it's not meta gamey at all, but the opposite because the characters know a lot of information which the players have no idea about.\$\endgroup\$
– motoDrizztAug 13 '18 at 12:27

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\$\begingroup\$I think this answer makes a strong case for using Monster Manual creatures as printed, but I also think the tone may be off-putting. I've upvoted this, but I think more folks would benefit from this answer were it to accommodate—rather than reject outright—the other more traditional answers.\$\endgroup\$
– Hey I Can ChanAug 13 '18 at 14:00

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\$\begingroup\$Are you saying that this specific case of monster modification is wrong or all of them? Is monster modification wrong only if the players don't know? If the latter it would seem that this falsely assumes modification and in-universe knowledge are mutually exclusive. You can both modify creatures (which is what the rules say and encourage already) and have that be in-character knowledge either by the DM explicitly telling players certain things or through in-character skill checks/RP.\$\endgroup\$
– RubiksmooseAug 13 '18 at 14:31

2

\$\begingroup\$@Rubiksmoose RE: "You can both modify creatures… and have that be in-character knowledge…." However, the question implies the DM didn't do that; instead, the DM tossed the accepted, printed notion of orcs don't use longbows and didn't replace in the PCs' knowledge scaffolding that knowledge with anything! To a brand new group, I can imagine that would seem like a betrayal: They lost what they believed was a reliable part of the game's fiction, and now they don't know what to expect in general. That degree of ambiguity bugs a lot of folks.\$\endgroup\$
– Hey I Can ChanAug 13 '18 at 14:58

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\$\begingroup\$@Rubiksmoose I totally agree. That's why I recommended the answer try to accommodate rather than reject the other more traditional views on this topic that other answers express. I mean, yeah, I think the answer's tone is too extreme, but, nonetheless, I think the answer raises a good point!\$\endgroup\$
– Hey I Can ChanAug 13 '18 at 15:22

Possibly

What the other answers to this question seems to be missing is the effect that DM fiat has on players.

The most important thing is that the players buy into any DM decisions, and a DM has to understand the effect of their decisions on the players, and also on the world at large.

Using the standard lore from the the monster manual builds a certain type of world, and if the players expect that world then any deviation can affect their immersion, and some players create their whole character to fit into the world they expect.

If the world is not what they expect then there are going to be problems.

So:
Talk to your players

If the players learn to expect these kind of deviations then they can set their expectations accordingly, and it is usually an easy transition to make, but throwing it on them in combat can be jarring.

If I was a player in this campaign and had build a character to have range in order to get an advantage over enemies like orcs and the DM pulled this kind of switch on me then I would be annoyed. If I never had the expectation in the first place, then I would have had a chance to not build in such a way, or the choice of building this way in full knowledge.

Never make a decision that disagrees with the players' idea of the world, or their place within it, without ensuring they are on board.